A short while ago Ben Goldacre asked Why don’t journalists link to primary sources?” when they report about scientific research.
I will add to this question by asking, why don’t journalists report the real results but always seem to bend them?
Today, while brushing my teeth I learned that my life is in grave danger. Why, because often I work more than 11 hours a day. According to the chap who read the news, more than 11 hours of work a day would increase my risk of coronary heart disease. Wow, time to change your life! Start working part-time…
The news spread like malignant cancer.
ABC was more concrete: “Study Links Long Working Hours to 67 Percent Hike in Risk of Cardiovascular Problems”.
The Press Association was a bit more lavish and blamed “Long hours” for an “increase” of “heart risks” .
While The Los Angeles Times warned that “Working longer hours may make the boss happy, but it could take a toll on your heart” .
Though all journalists have the same study in mind their assessment of what the results of this particular study are, differ quite considerably.
The respective study is published in the Annals of Internal Medicine, by Mika Kivimäki and nine co-authors and it is titled: “Using Additional Information on Working Hours to Predict Coronary Heart Disease (CDH). A Cohort Study.” The adjective “additional” is the important thing here. It says, there is something else present, apart from working hours. The authors included long working hours in a model to predict prevalence of CHD. Already in the model, we find other factors that increase the risk of CHD, like “age, sex, total cholesterol levels, high-density lipoprotein cholesterol levels, systolic blood pressure, and smoking habits” (p.458).
Say these latter mentioned variables form the base model to predict a person’s risk of falling victim to CHD over the next 10 years, would this person furthermore work more than 11 hours a day, the risk he already faces would improve by a further 4,7% percent. Thus , an accurate interpretation of the study’s results means that people who are male, above a certain threshold in age, above a certain total cholesterol level, and a certain density of lipoprotein cholesterol levels and who have a high blood pressure and smoke run an 4.7% increased risk of getting CHD when working for more than 11 hours.
So, no need to start working part-time unless you are a, high blood pressured smoking male, who is high lipoprotein dense, rather old and high on cholesterol.
Maybe journalist should start reading articles rather than abstracts or, as Ben Goldacre proposed, they should link to primary source, like that:
Kivimäki, Mika et al. (2011). Using Additional Information on Working Hours to Predict Coronary Heart Disease. A Cohort Study. Annals of Internal Medicine 154(4): 457-463.